1. Field of the Invention
The present invention relates to an intake air quantity controlling device for an internal combustion engine in which a collision portion of a driven-side gear collides with a full closure stopper and a full opening stopper, which are formed in a body, so that the driven-side gear stops rotating.
2. Description of the Related Art
In a conventionally known intake air quantity controlling device for an internal combustion engine which absorbs a collision load applied at the time when a driven-side gear collides with a full closure stopper or a full opening stopper, a driving-side gear and the driven-side gear are constructed as helical gears, one of which is coupled to a rotary shaft so as to be movable in a thrust direction with a cushioning member provided therebetween, as disclosed in JP 11-173166 A (FIGS. 1 and 2).
In the case of this intake air quantity controlling device, even when the driven-side gear hits the full closure stopper or the full opening stopper and stops all of a sudden, one of the gears moves in the thrust direction and the cushioning member absorbs a collision load applied at that moment.
In another known intake air quantity controlling device for an internal combustion engine, a collision portion colliding with a full closure stopper and a collision portion colliding with a full opening stopper are separately formed, as disclosed in JP 2003-120335 A.
However, in the aforementioned intake air quantity controlling device disclosed in JP 11-173166 A (FIGS. 1 and 2), the structurally complicated and costly helical gears must be used, and the cushioning member for causing the gear to slide with respect to the rotary shaft must be provided between the gear and the rotary shaft. There are problems in that the number of required parts increases accordingly, that the gear may not smoothly slide, and that the operation of mounting the cushioning member is bothersome.
In the aforementioned intake air quantity controlling device disclosed in JP 2003-120335 A, the costly helical gears are dispensable, and the cushioning member for causing the gear to slide with respect to the rotary shaft is unnecessary. However, since the collision portions are separately formed, problems of structural complication and volume augmentation are caused.